Category: north america

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historical / biographies minerals north america urban, art, anthropology

Preliminary study on a large scraper from Central Wyoming

Luke Sattler (USA) This paper is about an unusual artefact from Wyoming that may have been used by prehistoric people. It has now been studied and the preliminary research results are complete. This ancient scraper is a bifacial, thinned, cortical flaked tool, which means that its flakes were struck from the exterior of a chert nodule (hence the remaining cortex, or rough surface, visible on one face, Fig. 1). To make it bifacial, the edges were then flaked on both sides to form a cutting or scraping edge used for working with things like meat and hide, among others possibilities (Walker, Danny, Personal communication 2012). Fig. 1. Front and back view of bifacial scraper, showing flaking by ancient people in Wyoming. Rough surface of a chert nodule is revealed on the surface. (Photo by S Veatch.) The scraper is made out of chert, which is a sedimentary microcrystalline variety of quartz that forms when microcrystals of silicon dioxide grow within sediments. The microcrystals grow into irregularly shaped nodules or concretions, as dissolved silica is transported to the formation site by the movement of ground water or the sea. When there is more than one nodule or concretion forming at the same time and near to each other, they can join together and form large masses or layers of bedded chert. Some of the silicon dioxide in chert is thought to have a biological origin. In some oceans and shallow seas, large numbers of organisms have a silica-rich skeleton (for example, … Read More

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fossils north america palaeontology

Triassic fossils of West Texas

Rick Day (USA) I found my first Triassic fossil when I was about 15 years old on a backpacking trip in Tule Canyon, Briscoe County in Texas. After setting up camp, I walked over to a small, red-coloured hill. On its slope, I found a small, unusual bone fragment approximately 5cm by 5cm by 1cm and I remember being really excited. It was the first petrified bone I had ever found and it seemed strange to me. The bone fragment was flat on one side and had dimples and pits on the other side. It just didn’t look like anything I had ever seen before. Fig. 1. My first phytosaur skull. All the teeth and part of the rostrum is restored. Leptosuchus? I carried this unusual bone fragment in the glove compartment of my car for years, hoping to find someone who could identify it. However, I was never able to find anyone who knew anything about the fossil. Eventually, I became interested in geology and learned for myself the geology and paleontology of the region where I live. This eventually led to my becoming a science teacher. In time, I was able to identify my strange little fossil bone as being a scute fragment from the back armour of a Thecodont Reptile called an Ateosaur. (A “scute” is thickened, horny or bony plate that can be seen today on the shells of turtles or on the backs of crocodiles.) For those unfamiliar with Ateosaurs, these were the heavily armored … Read More

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extra-terrestrial geology north america space volcanoes

Lavas from Hawaiian volcano contain fingerprint of planetary formation

Dr Steve Koppes (USA) Hikers visiting the Kilauea Iki crater in Hawaii today walk along a mostly flat surface of sparsely vegetated basalt. It looks like parking lot asphalt, but, in November and December 1959, it emitted the orange glow of newly erupted lava. Now, a precision analysis of lava samples taken from the crater is giving scientists a new tool for reconstructing planetary origins. The results of the analysis, by the University of Chicago’s Nicolas Dauphas and his associates, were published in the 20 June 2008 issue of the journal Science. Fig. 1. Eruption Hill in Kilauea Iki crater on the Big Island of Hawaii. In December 1959, lava spurted 580m feet high from this location. Working with lava samples from the crater, scientists at the University of Chicago and elsewhere have devised a new tool for reconstructing planetary origins. (Photo: Steve Koppes.) The researchers selected Kilauea Iki for their study because scientists have drilled it for samples many times over the years as it cooled. This sequence of samples makes the lava lake a perfect site for studying differentiation – the separation of minerals and elements as magma cools and hardens. In particular, a close examination of iron isotopes – the slight variations the element displays at the subatomic level – can tell planetary scientists more about the formation of crust than they previously thought, according to Dauphas and co-authors, Fang-Zhen Teng of the University of Arkansas and Rosalind T Helz of the US Geological Survey. Dauphas informed … Read More

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geology museums, societies north america

Geology of Grandfather Mountain

Landis Wofford (USA) Like all mountains, the Blue Ridge Mountains of western North Carolina and Eastern Tennessee are the result of the action of plate tectonics. The crust of our planet is composed of five primary plates, or huge pieces of rock that move very slowly over deeper layers of hot, pliable rock. Some of the plates are composed of heavy oceanic crust, while others are made of lighter continental crust. At the middle of each oceanic plate, a large crack pours lava out onto the ocean floor. This causes oceanic plates to expand by an inch or two every year. When oceanic crust is forced against continental crust, the oceanic crust is pushed underneath the continental crust. When continental crust is forced against continental crust, huge mountains usually are formed. Fig. 1. View from the top of Grandfather Mountain. The Appalachian Mountains were formed in the remote past, some 200Ma, by collision of two continental crusts. During such mountain building, huge sheets of rock are pushed over each other. A rock layer called the Blue Ridge Thrust Sheet was moved over 60 miles to cover what is now Grandfather Mountain. These mountains were once ten times higher than they are today. Over hundreds of millions of years, erosion has carried away most of the rocks to form thick layers of sediment across the Piedmont, Coastal Plain, and in the Atlantic Ocean. Grandfather Mountain is the tallest mountain in the Blue Ridge and is now a popular tourist destination resort. … Read More

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fossils north america palaeontology

Collecting fossils in Florida

Niels Laurids Viby (Denmark) I didn’t go to Florida especially to look for fossils, but I am always looking for opportunities when I am abroad. Being an architect, I actually went there to study houses, in particular, the Art Deco district at Ocean Drive in Miami. However, it seems that every museum in the State (other than art museums) has a fossil exhibition: the Science museum in Miami was showing Chinese dinosaurs, the Orlando Science Centre had displays of Upper Cretaceous dinosaurs and the Natural History Museum in Gainesville had the very best – complete skeletons of mammals from Florida. Fig. 1. Fossil exhibition with complete skeletons of mammals from Florida, at the Natural History Museum in Gainesville. The result was that I spent a lot of time looking at things (including buildings) rather than finding fossils. In fact, out of thirteen days in Florida, I spent three in or waiting for planes, four driving long distances (but with some stops checking out potential fossil sites), four looking at houses, one on paperwork for a report on buildings and only one full day looking for fossils. The time spent driving was a big surprise. Florida looks small on a map of USA, but all of Denmark (my home country) could fit into the area south of Gainesville and the Danish population is probably equal in number to half of the people living in Greater Miami. However, I saw this trip as an expedition into unknown territory – a future trip … Read More

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fossils north america palaeontology

Coping with coprolites

Carl Mehling (USA) Generally, we have no use for it, or at least we convince ourselves we don’t, conveniently ignoring the fact that faeces of one kind or another (even our own) have fertilised our food for millennia. Organic waste products are an integral part of the living system and don’t tend to sit around for long. And it’s a good thing too, because, without the recycling of waste in Nature, we’d certainly be swamped by the stuff. Fig. 1. Ammonnite chamber steinkern composed of tiny invertebrate coprolites (Carl Mehling). Fig. 2. A probable Cretaceous crocodililian coprolites Fig. 3. The real thing? (Carl Mehling). Alas, this is a problem for students of coprolites – those droppings from Deep Time – as it reduces the probability of good coprolite fossils. However, everything in Nature has a story to tell, and there’s usually someone eager to listen, whomever or whatever that storyteller might be. I am one of those palaeontologists drawn to make order out of ordure and, thanks to the whims of the fossil record, enough of these now-inoffensive offerings have fortunately survived to the present. Fig. 4. A Triassic coprolite filled with fish bones (Carl Mehling). My first coprolite emerged from the Late Cretaceous marine sediments of Big Brook, New Jersey. It was a coprolite of spiral morphology – surprisingly common, once one’s search image is tuned – which my mentors credited to a shark. All ‘experts’, both amateur and academic, reflexively parroted this identification. Later, I learned that other … Read More

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